What do you guys think of people unleashing their dogs in public park

I have 2 young kids who are afraid of dogs and there are a few times already where they play in a park (e.x Garry point) and then approached by big dogs that are unleashed and then get frightened.

I know city bylaw requires dogs to be on leash all the time in parks but many people seems not to be following, and when I ask dogs owner to keep their dog on leash they become so hostile and start asking if their dogs have bothered me. Maybe from their perspective they haven’t but I can see my kids got frightened so it definitely bothers. They often call me a jerk but I got so confused as I’m simply asking them to follow city bylaw.

Thus I’m genuinely wondering is it really me overreacting? And what can I really do in this case? Thanks